Fixing a reversing light

Reverse lights are not a legal requirement, but they can be very useful. They serve two purposes: to warn other drivers that you are about to reverse, and to provide light if you are reversing in the dark. The circuit is a simple one, consisting of one or two rear light units that are turned on by a switch. If anything goes wrong with the circuit, it is easy to check. 

On most cars, the switch is mounted on the gear box and it is turned on automatically when reverse gear is selected. If the lights were added after the car was made, there may be a manual switch mounted on the dash. If you need a reversing light bulb, please visit, there you can find the model you need.

Blown Bulb

One of the most common problems is a blown bulb. To test it, remove it from its holder and connect it across the battery terminals with a short extension wire. If the bulb lights up, then the fault lies elsewhere in the circuit. 

Check if the bulbholder and wiring terminals are clean and bright. If there is any corrosion, clean it up with wet-or-dry paper then refit the bulb and retest. If the bulb still fails to light, then the fuse may have blown. Another sign that a fuse might have blown is if two reversing lights go together.


In many cases, the fuse that protects reversing lights also protects other parts. So if your reverse lights are not working and the rest of your car seems to be fine, then try renewing the fuse. If it blows again as soon as you test it, then there is a short circuit somewhere in your car. It may be easier to have an electrician find it for you.

Current Check

There are a few things you can do if your car is overheating. You can turn the ignition on and remove the feed wire to the coil to stop it from overheating. You can also select reverse gear or the 'R' position on an automatic. 

If the test lamp lights, that means current is reaching the bulb. If the bulb doesn't work, then there might be a problem with the earth lead. To check, you can run a short wire from the bulbholder earth to a point on the car body. If that fixes it, then you might need to renew the earth lead.

Wiring Check

If the current isn't reaching the bulb holder, you will need to check back along the rest of the circuit. To do that, find out what color and route of wires it takes along its path. Carefully probe these wires by following them with your hands. Sometimes they will disappear into a part of the circuit where you can't get to them, but if they are still inside a loom or something like that, you can bypass them with another wire.

Switch Test

If there is no current in the wiring, check the wires in your car. On a manual car, there will be two wires that need to be checked. On an automatic, there are four. Two of them are for the inhibitor circuit and should not be touched unless you are adjusting your switch (see sidebar on left). Check your manual to find out which terminals to test with a test light. You may need to raise up the car on axle stands so you can work under it better. 

Turn on the ignition and put it in reverse gear then connect one terminal of wire with a test lamp then move over and do another terminal if both light up, then something is wrong with wiring between switch and reversing lights or if only one terminal lights up than the switch is either needs to be adjusted or replaced. If the test light doesn't come on at all, check the wiring between fuse and switch. To replace a reversing light switch, disconnect all the wiring then unscrew the switch or if there is a locknut, release it. Replace the switch in reverse order and then adjust it.

Adjusting The Switch On A Manual Gearbox

You need to connect a circuit tester to the terminals. Choose reverse gear and loosen the locknut (right). Screw in the switch until it lights up, but not too high. When you turn off, do up the locknut again. Other switches are adjusted by unscrewing them completely and adding or taking away metal pieces (right) The setting is correct when the tester just lights up as you tighten it all the way.

Adjusting The Switch On An Automatic Gearbox

Some cars have adjustable automatic gearbox switches. You can usually adjust them by following these steps: Disconnect the four switch wires and terminals. Move the gear lever to the drive position. Slacken the locknut and screw the switch in a few turns. 

Connect a circuit tester with its own power supply (not a test lamp) across the two reversing light terminals. Slowly screw the switch in until the light goes out. Mark the switch and gearbox with paint so you know where they are supposed to be adjusted to.

Connect the circuit tester between the two inhibitor terminals. Screw the switch in further until it lights up again, and mark this position on the gearbox in line with the previous mark you made on the switch. Screw the switch out until its mark is exactly halfway between the two marks on the gearbox (below), then tighten the locknut.